Friction device



April 22, 1958 o -1 2,831,208

FRICTION DEVICE 2 Sheets-Sheet 1 Filed Dec. 3, 1953 April 22, 1958 R. e. MOHR FRICTION DEVICE 2 Sheets-Sheet 2 Filed Dec. 3, 1953 United FRICTION DEVICE Application December 3, 1953, Seriai No. 396,646

7 (Ilaims. (Cl. 16--86) This invention relates to a friction device for use with a school furniture book box lid or the like.

An object of the invention is to provide a device which allows a lid to be easily opened but retards its closing movement so that the lid cannot fall into a closed position and produce distracting noise or damage.

Another object is to provide a device operable as described above and of simple and compact construction and substantially entirely enclosed by a covering member to prevent damage to or injury from the parts thereof.

Another object of the invention is to provide a device to function as described above embodying first and second spaced side members secured to the box in operable relation with a central member secured to and extending from the lid for arcuate movement therewith between the spaced side members, a leather friction element fixedly mounted on said first side member for frictional engagement with said central member, a block positioned in a cavity in the second side member and carrying a leather friction element for engagement with the central member and being constructed and arranged for sliding movement in said cavity from a lower retarding position wherein the leather friction element is in close frictional engagement with the central plate to retard the downward movement of the lid, and an upper non-retarding position wherein the leather friction element is in loose frictional engage ment with said central member to allow substantially free opening movement of the lid.

Other objects and advantages will be apparent from the description and drawings, in which:

Fig. 1 is a front elevational view, partially broken away to show thepositioningof two friction devices in a book box or "the like;

Fig. 2 is a fragmentary side view along the line 2--2 of Fig. 1;

Fig. '3 is a sectional view taken along the line 3--3 of Fig. 2;

Fig. 4 is a fragmentary view similar to Fig. 3 but with the lid and central member in a raised position;

Fig. 5 is a sectional view taken along theline 55 of Fig.3;

Fig. 6 is a front levational view of the block friction element;

Fig. 7 is aside elevation of said element;

Fig. 8 is a front'elevational View of the cylindrical leather friction element; and

Fig. 9 is a sideelevation of said cylindrical leather friction element.

While this invention is susceptible of embodiment in many different forms, there is shown -in the drawings and will-hereinafter be described in detail one specific embodiment, with the understanding that the present disclosure is to'b'e considered as an exemplification of the principles of theinvention and is-notintended tolimit the invention to the embodiment illustrated. The scope of p'a'rts'o'f the friction device positioned adjacent th'e right tates 1 atent side of the book box are designated by primed numbers. friction devices 1 and 1 are shown associated with the lid 2 of a conventional book box 3 of a school desk and, insofar as the structure of one involves reverse construction of the other, only friction device 1 is hereinafter specifically described.

Metal tubular members 4 and 5 are secured along the upper extremities of the back 6, front 7, and sides ;8 of the box to form a closure contact with the lid 2, hinged to the back of the box by any suitable means such as by two leaf-type hinges (Fig. 2) each with a pivotable leaf 9 secured to the lid as by screws and a leaf 10 secured to the back 6 of the box as by spot welding. The hinges have been omitted from the other figures for clarity.

Generally, the friction device is comprised of a pair of substantially vertically extending, spaced metal side plates 11 and 12 (Figs. 2 to 5), a metal central plate 13 secured to and extending from the lid 2. and positioned intermediate the side plates for arcuate movement with the lid between open and closed positions and retarding or friction elements positioned between each side plate and the adjacent face of the central plate. I

Side plate 12 is secured to the rear portion of the side plate 11 (Figs. 2 and 5) by bolt 15 and any suitable means as by spot welds 16 or by coin lugs adjacent bolt 15 on one side plate positioned to fit into corresponding holes in the other side plate. Plate 11 is attached to the rear wall 6 of the box by means of an integral inwardly turned flange 18 laterally disposed inwardly toward the center of the box from the hinge leaf 10 and spot welded to the rear wall, as indicated at 17. The front portion of plate 11 is turned to form an L-shaped flange having a portion 19 (Fig. 5) extending toward the adjacent side 8 of the box and a portion 20 parallel to the side and secured thereto as by spot welds 21. The top of plate 11 is turned to form flange 22 positioned against the bottom of tubular member 4. The bottom 23 of said plate extends'rearwardly at a slight upward inclination as shown in Fig. 2.

Plate 11 has an offset at 24 (Fig. 5) to form a space 25 between plates 11 and 12 in which the central plate 13 is movably positioned. i

The top extremity 27 of plate 12 terminates in the same horizontal plane as the top of flange 22 of plate 11 and the rear edge of plate 12 extends downwardly closely adjacent and substantially parallel to the back 6 of the box to terminate at a point substantially below plate 11. The lower and front portions of plate 12 are turned to form a flange 28 extending toward the side 8 of the box. Plate 12 thus serves also to compactly enclose central plate 13 and side plate 11 against the side 8 of the box.

The central plate 13 extends from the bottom of lid 2, the screws 29 securing a top metal flange 30 of said plate to the lid. An arcuate front edge of the central plate begins at 31 (Fig. 2) and terminates at the lower extremity of the plate adjacent a hook portion 32. A bolt 32a, threadably received in a nut fastened to plate 11, passes through plates 11 and 12 in a position closely adjacent the arcuate edge of the central plate and operates as a stop for the hook 32 when the lid is raised to its fully open position.

A recessed circular cavity 33 is provided in the surface of side plate 11 adjacent the central plate to receive a friction element comprising a disc of leather 34. one face of which is in continuous frictional engagement With the adjacent side of the central plate. i

The face of side plate 12, adjacent to the central plate, is provided with a somewhat rectangular shaped cavity 36 having sides, top and bottom sloping generally towards each other and away from the arcuate central plate. The cavity has a rear wall 38 (Figs. 3 and 4) inclined upwardly and outwardly from the central plate so that thecavity is of a greater depth at its top than at its bottom. A shiftable friction element in the form of a block 39 of substantially the same shape as the lower portion of the cavity is seated therein and carries in a recess in its inner face a substantially rectangular leather friction element 4! having its outer surface 41 in position to have continuous frictional engagement with the adjacent side of the central plate. The block may be comprised of any suitable material as a plastic, such as polyethylene, a polyvinyl solid, or nylon, or an oil impregnated powdered metal, such as iron.

The friction elements operate to retard the closing of lid 2, and to permit the somewhat free opening movement thereof and to this end the plastic block 39 may shift in its cavity 36 between a lower retarding position and an upper non-retarding position.

When the lid is moving towards or is in its closed position, the block is in its retarding position as shown in Fig. 3, but as the lid is opened, frictional contact between the central plate 13 and leather element. 40 causes the block to move upwardly in its cavity and, by virtue of the inclined rear wall 38 of the cavity, away from the central plate; thus reducing the retarding or frictional I effect of the leather element on the central plate to allow the lid to be easily opened.

When the lid is being closed, frictional contact between the leather element and the central plate causes the block to move downwardly in its cavity and by virtue of the inclined rear wall of the cavity, toward the central plate; thus increasing the frictional force'of'the leather face on the central plate, and in effect, squeezing the plate between the two frictional elements, to retard the downward movement of the lid. Frictional force exerted by the two leather elements may be varied by adjusting bolt 32a to vaiy the distance between the side plates adjacent the friction elements. Thus it may be seen that l have provided a friction device embodying a pair of spaced side plates mounted within a book box and a central plate movable therebetween with the motion of a lid carrying the central plate. A friction element is fixed on one side plate for continuous engagement with the adjacent side of the central plate and a friction element slidable in a cavity in the other side plate engages the other side of thecentral plate. The construction and arrangement is such that when the lid is being opened and the central plate moves upwardly, frictional contact between the movable friction element and the central plate causes said element to move v upwardly in the cavity and, by virtue of the inclined rear wall of the cavity, away from the adjacent surface of the central plate As the friction element moves away from the central plate, the central plate flexes slightly toward the friction element and away from the fixed friction element on the other side plate. Thus, as the lid is opened, the frictional effect of both the fixed and movable friction elements is substantially reduced so that the lid may be easily opened. When the lid is being closed, the movable friction element will, by virtue of frictional contact with the central plate, move downwardly along the sloping rear wall of the cavity toward the central plate and into a lower position wherein the element is wedged between the cavity rear wall and the central plate thus forcing the central plate to flex slightly toward the fixed friction element so that both elements exert maximum frictional effect on the central member to retard the closing movement of the lid. Bolt 32a isprovided for adjusting the distance between the two side plates so as to increase or decrease the frictional effect of the elements and, if desired, to make the device operable for maintaining the lid in an open position so that a person may use both hands to place an article in .or remove it from the book box without having to manually support the lid.

I claim:

1. A friction device associated with the lid of a school furniture book box and operative to permit substantially 4 free openings movement of the lid and to retard the closing movement thereof comprising, vertically extending first and second spaced metal side plates secured to said book box adjacent a side thereof, a vertical metal central plate secured to and extending from the bottom of said lid and positioned intermediate said side plates for arcuate movement with said lid between open and closed positions, said first side plate having a cylindrical cavity opening toward the central plate, a cylindrical leather element fixed in said cavity and having one surface adjacent said central plate and in frictional engagement therewith during the opening and closing movements of the lid, said second side plate having a cavity with a generally rectangular opening adjacent the central plate and opposed to the cavity in said first side plate, said second cavity having convergingly inclined sides extending away from the central plate and a rear wall upwardly and outwardly inclined from said central plate so that said cavity is of a greater depth at its top than at its bottom, a blockhaving a shape correspond ing to the lower portion of said cavity and slidably positioned therein, a rectangular leather element fixed on said block and having .one surface in frictional engagement with the adjacent side of the central plate, said block being positioned to move in said cavity between a lower retarding position wherein said block is in wedging engagement with said cavity rear wall and the leather element thereon is in close frictional contact with the central plate to hold the lid in an open position and an upper non-retarding position wherein said block is in loose engagement with said cavity and said leather element is in loose substantially reduced frictional contact with the central plate, the central plate when raised by opening movement of the lid aiding movement of the block to the non-retarding position whereby the lid may be easily raised and said central plate when lowered by closing movement of the lid aiding movement of the adjusting means for adjusting the frictional effect of said iii leather elements.

3. The structure in accordance with claim 2 and including means provided on the bottom of said central plate for contact with said adjusting means for limiting the upward movement of the central plate when the lid is in an open position. i

4. The structure in accordance with claim 3 and including flange means to substantially enclose the central plate and first side plate between said second side plate and the adjacent side of the book box.

5. A friction device operable with the lid of a school furniture book box, comprising a central member having parallel side portions and secured to and extending from said lid for movement therewith between open and closed positions, a first side member secured to said box and positioned adjacent one side of said central member, friction means mounted on said first side member and in frictional engagement with said central member, a second side member secured to said first side member and having a portion spaced therefrom adjacent the other side of said central member, said spaced portion having a cavity opening toward the adjacent side of the central member, said cavity having a rear wall inclined outwardly from said central member so that the cavity is of a greater depth at one end than at the other, friction means slidably positioned in said cavity for frictional engagement with the adjacent side of the central member and operable for movement in said cavity between a first position wherein said slidable friction means is in close engagement with said cavity and in close frictional contact with the central member and a second position member when actuated by opening movement of the lid aiding movement of said slidable friction means to the second position whereby the lid may be easily opened and said central member when actuated by closing movement of the lid aiding movement of said slidable friction means to the first position to retard downward movement of said lid.

6. A friction device operable with the hinged lid of a book box or the like comprising, a first member with parallel side portions and fixed to and extending from said lid, means positioned in frictional engagement with one side portion of said member, a second member mounted in said box adjacent the other side portion of said first member and having slidable means mounted thereon in frictional engagement with said other side portion of said first member, means efiective in response to movement of said first member during closing movement of the lid for causing said slidable means to increase the frictional force on the first member to retard the closing movement of the lid, and said last recited means being effective in response to movement of said first member upon opening movement of the lid for causing said slidable means to substantially reduce the frictional force on the first member.

7. A friction device operable with a hinged element, comprising, a first member movable with the hinged element, a second member stationarily mounted adjacent the path of movement of the first member, a friction block to the inclined wedging surface to create a minimum frictional force between said friction block and said other member during movement of the hinged element in one direction, and being slidably displaceable by said other member in the opposite direction relative to the inclined wedging surface in response to movement of the hinged element in the opposite direction for increasing the frictional force between said friction block and said other member.

References Cited in the file of this patent UNITED STATES PATENTS 1,026,781 Bahnsen May 21, 1912 1,791,691 Stevens Feb. 10, 1931 1,976,081 Merrill Oct. 9, 193 4 2,287,563 Persson June 23, 1942 2,723,776 Jacobson Nov. 15, 1955 

